As being well known, it is open to possibility of forgery and alternation for all sorts of cards such as a cash card or credit card, all sorts of certificate such as a passport, an insurance policy and a driving license, checks or securities, paper money, an industrial product material being rendered an information such as a brand or produced record, a food label being rendered an information such as producing district or producing time.
To prevent forgery or alternation for such matters, it has been conventionally carried to attach a mark having magnetic properties or a mark absorbing and reflecting an electromagnetic wave or a mark emitting fluorescence by a visual ray, and then distinguish an authentic matter from a spurious article which the said mark is not attached or the other mark is attached. For example, it may be consisted of irradiating an electromagnetic wave of a determined wave area, detecting a fluorescence being radiated from the said information rendering materials by such irradiation of an electromagnetic wave, and discriminating forgery or alternation for such matters according to the said detected result of fluorescence.
In these days, an automatic sorting or identifying elements have been used by enabling to measure absorption and reflection of infrared ray being ranged of wavelength (700˜1600 nm) with a device since a semiconductor laser having a range of infrared ray of the said wavelength that can not be recognized with a naked eye had been developed as a light source to recognize and detect an image.
To carry out such discrimination of alternation promptly, it is necessary to use the materials that enable to detect in real time as respond within short time with employment of the material being responsive to a gamma ray. However, there had been not known the materials that respond to high energy among the known compounds being used in a mark for preventing forgery or alternation so that radioactive elements or compounds that respond with absorption of low energy have been used in the form of combination, which makes it difficult to prompt decision of forgery or alternation because the velocity responsive to a gamma ray is slow as well as an amounts of absorption are of small quantity.